Materials and methods for immunizing against FIV infection

ABSTRACT

The subject invention pertains to methods and compositions for protecting feline animals from infection by FIV using immunogens derived from primate immunodeficiency viruses, including HIV and SIV. Methods for vaccinating feline animals with the subject vaccine compositions are described. Feline animals vaccinated according to the methods and compositions of the subject invention exhibit protective humoral and cellular immune responses to FIV when challenged with FIV.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser. No. 60/470,066, filed May 12, 2003, which is hereby incorporated by reference in its entirety, including all figures, nucleic acid sequences, amino acid sequences, and tables.

The subject invention was made with government support under a research project supported by National Institutes of Health Grant No. NIH AI30904. The government has certain rights in this invention.

BACKGROUND OF THE INVENTION

Domestic cats are subject to infection by several retroviruses, including feline leukemia virus (FeLV), feline sarcoma virus (FeSV), endogenous type C oncoronavirus (RD-114), and feline syncytia-forming virus (FeSFV). Of these, FeLV is the most significant pathogen, causing diverse symptoms including lymphoreticular and myeloid neoplasms, anemias, immune-mediated disorders, and an immunodeficiency syndrome that is similar to human acquired immune deficiency syndrome (AIDS). Recently, a particular replication-defective FeLV mutant, designated FeLV-AIDS, has been more particularly associated with immunosuppressive properties.

The discovery of feline T-lymphotropic lentivirus (now designated as feline immunodeficiency virus, FIV) was first reported in Pedersen et al. (1987). Characteristics of FIV have been reported in Yamamoto et al. (1988a); Yamamoto et al. (1988b); and Ackley et al. (1990). Seroepidemiologic data have shown that infection by FIV is indigenous to domestic and wild felines throughout the world. A wide variety of symptoms are associated with infection by FIV, including abortion, alopecia, anemia, conjunctivitis, chronic rhinitis, enteritis, gingivitis, hematochezia, neurologic abnormalities, periodontitis, and seborrheic dermatitis. The immunologic hallmark of domestic cats infected with FIV is a chronic and progressive depletion of feline CD4⁺ peripheral blood lymphocytes, a reduction in the CD4:CD8 cell ratio and, in some cases, an increase in CD8-bearing lymphocytes. Based on molecular, biochemical and immunopathologic characteristics, FIV infection of cats is now considered to be a better feline AIDS model than FeLV-FAIDS.

Cloning and sequence analysis of FIV has been reported in Olmsted et al. (1989a); Olmsted et al. (1989b); and Talbott et al. (1989). Hosie and Jarrett (1990) described the serological response of cats infected with FIV. FIV virus subtypes can be classified according to immunotype based on the level of cross-neutralizing antibodies elicited by each strain (Murphy and Kingsbury, 1990). Recently, viruses have been classified into subtypes according to genotype based on nucleotide sequence homology. Although HIV and FIV subtyping is based on genotype (Sodora et al., 1994; Rigby et al., 1993; and Louwagie et al., 1993), little is known about the correlation between the genotype and immunotype of subtypes. FIV viral isolates have been classified into four FIV subtypes: A, B, C and D. (Kakinuma et al., 1995). Infectious isolates and infectious molecular clones have been described for all FIV subtypes except for subtype C (Sodora et al., 1994). Subtype C FIV has only been identified from cellular DNA of cats from Canada (Sodora et al., 1994; Rigby et al., 1993; Kakinuma et al., 1995). FIV strains identified in the art include (subtype of the strain is shown in parenthesis) Petaluma (A), Dixon (A), UK8 (A), Dutch113 (A), Dutch19K (A), UK2 (A), SwissZ2 (A), Sendai-1 (A), USCAzepy01A (A), USCAhnky11A (A), USCAtt-10A (A), USCAlemy01 (A), USCAsam-01A (A), PPR (A), FranceWo, Netherlands, Bangston (A/B), Aomori-1 (B), Aomori-2 (B), USILbrny03B (B), TM2 (B), Sendai-2 (B), USCKlgri02B (B), Yokohama (B), USMAsboy03B (B), USTXmtex03B (B), USMCglwd03B (B), CABCpbar03C (C), CABCpbar07C (C), CABCpady02C (C), Shizuoka (D), and Fukuoka (D).

One concern with the use of FIV-derived immunogens in a vaccine is that veterinary practitioners may be unable to tell whether a cat that tests positive for antibodies to FIV or FIV proteins has been infected with FIV or if the antibodies resulted from the cat being vaccinated against FIV using FIV-derived immunogens. Thus, there remains a need in the art for a vaccine that protects against FIV infection but that allows the practitioner to determine whether antibodies to FIV are a result of infection or immunization of a cat.

BRIEF SUMMARY OF THE INVENTION

The subject invention pertains to methods and compositions for protecting feline animals from infection by FIV using immunogens derived from primate immunodeficiency viruses, including HIV and SIV. Methods and compositions for vaccinating feline animals with the subject vaccine compositions are described. Feline animals vaccinated according to the methods and compositions of the subject invention exhibit protective immune responses to FIV when challenged with FIV.

The subject invention also concerns methods for selecting for epitopes that are evolutionarily conserved among immunodeficiency viruses. Evolutionarily conserved epitopes of immunodeficiency viruses identified using methods of the present invention also constitute part of the invention. The subject invention further concerns methods for protecting humans and other animals against infection by immunodeficiency viruses, such as HIV and FIV.

BRIEF DESCRIPTION OF THE SEQUENCES

SEQ ID. NO: 1 is an amino acid sequence of an HIV-1_(UCD1) envelope protein.

SEQ ID NO: 2 is an amino acid sequence of an HIV-1_(UCD1) gag protein.

SEQ ID NO: 3 is a nucleotide sequence of an HIV-1_(UCD1) polynucleotide encoding an envelope protein.

SEQ ID NO: 4 is a nucleotide sequence of an HIV-1_(UCD1) polynucleotide encoding a gag protein.

SEQ ID. NO: 5 is an amino acid sequence of an HIV-1_(IIIB) envelope protein.

SEQ ID NO: 6 is an amino acid sequence of an HIV-1_(IIIB) gag protein.

SEQ ID NO: 7 is a nucleotide sequence of an HIV-1_(IIIB) polynucleotide encoding an envelope protein.

SEQ ID NO: 8 is a nucleotide sequence of an HIV-1_(IIIB) polynucleotide encoding a gag protein.

DETAILED DISCLOSURE OF THE INVENTION

The subject invention concerns materials and methods for protecting a feline animal from infection by FIV by administering to the animal immunogens derived from primate immunodeficiency viruses, such as human immunodeficiency virus (HIV) or simian immunodeficiency virus (SIV). In one embodiment, an effective amount of a composition comprising an immunogen or immunogens derived from a primate immunodeficiency virus is administered to a feline animal. In addition, the various immunogen compositions described herein can be used separately and in combination with each other.

Advantageously, the present invention allows for protection against FIV infection wherein the generation of an immune response against FIV in the animal allows a veterinarian or other person of ordinary skill in the art to determine whether an animal's immune response to FIV or FIV immunogens or antigens is a result of an immunization to protect against FIV infection or if it is a result of FIV infection in the animal. In one embodiment, animals immunized using a vaccine composition of the present invention do not produce antibodies that cross-react with FIV gp95. Animals that have been infected with FIV or that may have received vaccines containing FIV-derived immunogens or antigens produce antibodies that bind to FIV gp95. Feline animals encompassed within the scope of the present invention include domestic house cats, feral cats, and other wild cats including bobcat, cougar, mountain lion, tiger, jaguar, leopard, puma, cheetah, and lion.

The present invention can also be used to generate an immune response, cellular and/or humoral, against FIV in a feline animal using immunogens derived from primate immunodeficiency viruses, such as HIV and SIV. In one embodiment, an amount of an immunogen sufficient to induce an immune response against FIV is administered to a feline animal. Serum antibodies from immunized cats can be tested for virus neutralizing antibody activity against HIV using PBMCs from healthy HIV-uninfected humans as indicator cells. Lymphocytes from immunized cats can be tested for both HIV-specific T-helper (Th) and cytotoxic T lymphocyte (CTL) activities. Th and CTL activity can be measured by the level of Th cytokines and CTL cytotoxins produced by the lymphocytes from unimmunized and immunized cats in response to in vitro stimulation with inactivated HIV whole-virus that are either the same as (homologous) or different from (heterologous to) the immunogen strain(s). The inactivated heterologous strains used for the in vitro stimulation can be from the same or different subtypes as the immunogen strain(s). Preferred immunogens produce high levels of Th cytokines in the cultures with CD4⁺ T lymphocytes from immunized cats and is indicative. Similarly, preferred immunogens produce high levels of CTL cytotoxin(s) by CD8⁺ T lymphocytes from immunized cats.

Primate immunodeficiency viruses encompassed within the scope of the present invention include HIV and SIV. In regard to HIV, the virus can be from either HIV-1 or HIV-2. In one embodiment, the HIV is HIV-1. Several distinct strains of HIV-1 have been described in the art and include HIV-1_(IIIB), HIV-1_(UCD1), HIV-1_(LAV), and HIV-1_(BRU). In an exemplified embodiment described herein, immunogens of the present invention are derived from the strain of HIV-1 designated as HIV-1_(IIIB) and/or HIV-1_(UCD1). SIV strains included within the scope of the invention are SIV_(syk), SIV_(smm), SIV_(mac), SIV_(mnd), SIV_(l'hoest), SIV_(agm) and SIV_(cpz) (Whetter et al., 1999). The nucleotide sequences of numerous HIV and SIV genes have been described in the scientific literature, deposited in sequence databanks, such as the NCBI Genbank, and have been disclosed in published patent applications and issued patents. For example, complete genome sequences of HIV-1 and HIV-2 isolates are disclosed at Genbank accession numbers NC 001802 and NC 001722. Similarly, amino acid sequences of proteins encoded by HIV and SIV genes have been disclosed and are well known in the art. Sequences of HIV are also disclosed in databases available at the website http://www.hiv.lanl.gov/content/index. Genes of primate immunodeficiency viruses that encode proteins include env, gag, pol, and nef

Immunogens derived from primate immunodeficiency viruses can be in isolated form or provided in any suitable composition. Preferably, the primate immunodeficiency viral immunogens are provided in a composition and administered in a manner to induce a strong cell-mediated and humoral immune response to the immunogen in a feline animal. In one embodiment, immunogens can be provided in the form of virus infected cells or whole cell-free virus. Virus in virus-infected cells and cell-free virus can be treated in a manner to inactivate or attenuate the virus. Methods for inactivating or attenuating virus are known in the art, and include, for example, treatment with paraformaldehyde, formalin, phenol, UV light, elevated temperature and the like. U.S. Pat. No. 6,503,753 describes methods for photoinactivation of HIV reverse transcriptase which thereby inactivates the HIV virus. Primate immunodeficiency viruses can also be prepared that are replication-defective. U.S. Pat. No. 6,500,623 describes HIV replication-defective viral particles and means for producing them. Other techniques for producing inactivated, attenuated and replication defective viruses are known in the art.

In another embodiment, immunogens of the invention are derived from viral proteins, or immunogenic fragments or variants thereof, of primate immunodeficiency viruses. Proteins that can be utilized as immunogens in the present invention include, but are not limited to, proteins encoded by the env, gag, pol, tat, rev, and/or nef genes. In one embodiment, envelope proteins encoded by the env gene that can be used in the invention include the envelope proteins gp120 and gp160, including fragments thereof, fusions of gp120 and gp160, and variations of gp120 and gp160, including variations in glycosylation which includes gp120 and/or gp160 proteins that are unglycosylated. A cellular protein cleaves gp160 into gp41 and gp120 moieties. The gp41 moiety comprises the transmembrane domain of the envelope protein, whereas gp120 is located on the surface of the infected cell or virion. The gp120 molecule consists of a polypeptide core of approximately 60 kd, but N-linked glycosylation can increase the molecular weight of the protein to approximately 120 kd. The viral envelope proteins used in conjunction with the present invention can be either unclipped or clipped (see, for example, U.S. Pat. No. 5,849,533). Envelope protein variants have been described in U.S. Pat. No. 5,846,546. Synthetic peptides which immunologically mimic HIV gp120 and/or gp160 envelope proteins can also be used in the present invention (see, for example, U.S. Pat. No. 5,763,160). In an exemplified embodiment, a combination of gp120 and gp160 envelope protein from HIV-1_(IIIB) is utilized as an immunogen. In one embodiment, the envelope polypeptide of HIV-1_(UCD-1) comprises the amino acid sequence shown in SEQ ID NO: 1. In one embodiment, the envelope polypeptide of HIV-1_(IIIB) comprises the amino acid sequence shown in SEQ ID NO: 5.

Proteins encoded by a primate immunodeficiency virus gag gene, such as the p17 matrix protein, the p24 capsid protein, and the p7 nucleocapsid protein of HIV and the p27 protein of SIV, and fragments and variants thereof, can also be used in accordance with the present invention. In an exemplified embodiment, a p24 protein from HIV-1_(UCD-1) is utilized as an immunogen. In one embodiment, the p24 polypeptide of HIV-1_(UCD-1) comprises amino acids 132 to 362 of SEQ ID NO: 2. In one embodiment, the p24 polypeptide of HIV-1_(IIIB) comprises amino acids 132 to 363 of SEQ ID NO: 6. Immunological fragments of the p24 protein have been described in U.S. Pat. No. 5,700,469. Proteins encoded by a primate immunodeficiency virus pol gene, such as reverse transcriptase (RT) protease (PR), and Rnase H of HIV, and fragments and variants thereof, can also be used in the present invention. Endonuclease protein p31 of HIV, and fragments and variants thereof, which is a protein encoded at the 3′-end of the pol gene of HIV, can also be used in accordance with the present invention. Immunological peptide fragments of the p31 protein of HIV have been described in U.S. Pat. No. 5,401,628. Regulatory proteins encoded by tat and rev genes of primate immunodeficiency viruses, and accessory proteins encoded by nef vif, vpr, vpu, and vpx genes of primate immunodeficiency viruses, and fragments and variants of these proteins, can also be used in the present invention.

Peptides corresponding to immunogenic or antigenic regions of primate immunodeficiency viruses can be synthesized or prepared by recombinant means and utilized in the methods of the present invention. In one embodiment, peptides that correspond to overlapping fragments of a primate immunodeficiency virus protein can be prepared and used in the methods of the present invention. Any suitable combination of the peptide fragments can be used for immunizing an animal according to methods of the present invention. For example, peptide fragments that correspond to the carboxy terminus region of a viral protein can be used with peptide fragments that correspond to an amino terminus region or a transmembrane region of the protein.

Recombinant virus or viral vector-based expression constructs that comprise, primate immunodeficiency virus nucleotide sequences, for example, HIV or SIV env, gag, pol, tat, rev, nef, vif, vpu, vpr, gag/pol, or env-gag/pol sequences, or fragments or variants thereof, are also contemplated for use with the present invention. Any suitable viral vector that can be used to prepare recombinant vector/HIV or recombinant vector/SIV constructs is contemplated for use with the subject invention. For example, viral vectors derived from adenovirus, avipox, feline herpesvirus, vaccinia, canarypox, entomopox, swinepox and others known in the art can be used with the compositions and methods of the present invention. Recombinant polynucleotide vectors that encode and that can express HIV or SIV components in a suitable host cell can be constructed using standard genetic engineering techniques known in the art.

DNA or RNA vaccines which comprise nucleic acid that encodes one or more primate immunodeficiency virus proteins, or a fragment or variant thereof, are also contemplated for use in the subject invention. The nucleic acid can be provided in the form of a plasmid or eukaryotic expression construct. DNA vaccines and formulations have been described, for example, in published patent applications 20040076632; 20040047878; 20040009941; 20020156037; 20020032165; and 20010004531.

As used herein, the term “expression construct” refers to a combination of nucleic acid sequences that provides for transcription of an operably linked nucleic acid sequence. As used herein, the term “operably linked” refers to a juxtaposition of the components described wherein the components are in a relationship that permits them to function in their intended manner. In general, operably linked components are in contiguous relation.

Expression constructs of the invention will also generally include regulatory elements that are functional in the intended host cell in which the expression construct is to be expressed. Thus, a person of ordinary skill in the art can select regulatory elements for use in, for example, bacterial host cells, yeast host cells, plant host cells, insect host cells, mammalian host cells, and human host cells. Regulatory elements include promoters, transcription termination sequences, translation termination sequences, enhancers, and polyadenylation elements.

An expression construct of the invention can comprise a promoter sequence operably linked to a polynucleotide sequence encoding a peptide of the invention. Promoters can be incorporated into a polynucleotide using standard techniques known in the art. Multiple copies of promoters or multiple promoters can be used in an expression construct of the invention. In a preferred embodiment, a promoter can be positioned about the same distance from the transcription start site as it is from the transcription start site in its natural genetic environment. Some variation in this distance is permitted without substantial decrease in promoter activity. A transcription start site is typically included in the expression construct.

For expression in animal cells, an expression construct of the invention can comprise suitable promoters that can drive transcription of the polynucleotide sequence. If the cells are mammalian cells, then promoters such as, for example, actin promoter, metallothionein promoter, NF-kappaB promoter, EGR promoter, SRE promoter, IL-2 promoter, NFAT promoter, osteocalcin promoter, SV40 early promoter and SV40 late promoter, Lck promoter, BMP5 promoter, TRP-1 promoter, murine mammary tumor virus long terminal repeat promoter, STAT promoter, or an immunoglobulin promoter can be used in the expression construct.

Expression constructs of the invention may optionally contain a transcription termination sequence, a translation termination sequence, signal peptide sequence, and/or enhancer elements. Transcription termination regions can typically be obtained from the 3′ untranslated region of a eukaryotic or viral gene sequence. Transcription termination sequences can be positioned downstream of a coding sequence to provide for efficient termination. Signal peptides are a group of short amino terminal sequences that encode information responsible for the relocation of an operably linked peptide to a wide range of post-translational cellular destinations, ranging from a specific organelle compartment to sites of protein action and the extracellular environment. Targeting a peptide to an intended cellular and/or extracellular destination through the use of operably linked signal peptide sequence is contemplated for use with the immunogens of the invention. Chemical enhancers are cis-acting elements that increase gene transcription and can also be included in the expression construct. Chemical enhancer elements are known in the art, and include, but are not limited to, the cytomegalovirus (CMV) early promoter enhancer element and the SV40 enhancer element. DNA sequences which direct polyadenylation of the mRNA encoded by the structural gene can also be included in the expression construct.

Unique restriction enzyme sites can be included at the 5′ and 3′ ends of the expression construct to allow for insertion into a polynucleotide vector. As used herein, the term “vector” refers to any genetic element, including for example, plasmids, cosmids, chromosomes, phage, virus, and the like, which is capable of replication when associated with proper control elements and which can transfer polynucleotide sequences between cells. Vectors contain a nucleotide sequence that permits the vector to replicate in a selected host cell. A number of vectors are available for expression and/or cloning, and include, but are not limited to, pBR322, pUC series, M13 series, and pBLUESCRIPT vectors (Stratagene, La Jolla, Calif.).

Polynucleotides, vectors, and expression constructs of the invention can also be introduced in vivo via lipofection (DNA transfection via liposomes prepared from synthetic cationic lipids) (Felgner et al., 1987). Synthetic cationic lipids (LIPOFECTIN, Invitrogen Corp., La Jolla, Calif.) can be used to prepare liposomes to encapsulate a polynucleotide, vector, or expression construct of the invention. A polynucleotide, vector, or expression construct of the invention can also be introduced as naked DNA using methods known in the art, such as transfection, microinjection, electroporation, calcium phosphate precipitation, and by biolistic methods.

As used herein, the terms “nucleic acid” and “polynucleotide sequence” refer to a deoxyribonucleotide or ribonucleotide polymer in either single- or double-stranded form, and unless otherwise limited, would encompass known analogs of natural nucleotides that can function in a similar manner as naturally-occurring nucleotides. The polynucleotide sequences include both the DNA strand sequence that is transcribed into RNA and the RNA sequence that is translated into protein. The polynucleotide sequences include both full-length sequences as well as shorter sequences derived from the full-length sequences. It is understood that a particular polynucleotide sequence includes the degenerate codons of the native sequence or sequences which may be introduced to provide codon preference in a specific host cell. The polynucleotide sequences falling within the scope of the subject invention further include sequences which specifically hybridize with the exemplified sequences. The polynucleotide includes both the sense and antisense strands as either individual strands or in the duplex.

The methods of the present invention contemplate a primary immunization with a vaccine composition of the invention. Subsequent or secondary immunizations are also contemplated within the scope of the subject methods. The vaccine composition used for secondary immunizations can be the same as or vary from the composition used for primary immunization. For example, primary immunizations of an animal may use recombinant vector-based HIV or SIV constructs, having single or multiple strain components, followed by secondary boosts with vaccine compositions comprising HIV- or SIV-infected cell lines, or HIV or SIV polypeptides, or cell free HIV or SIV virus, also having single or multiple strain components. Primary immunizations can also use an HIV and/or SIV DNA vaccine. In one embodiment, a recombinant vector construct is used for the primary immunization, whereas a protein, or protein plus recombinant vector construct, subunit vaccine composition is used for secondary boosts. In addition, the subject invention contemplates methods wherein the immunogen(s) used for a primary immunization is an HIV or SIV derived immunogen, e.g., an HIV p24 protein, and the immunogen(s) used for secondary immunizations are derived from FIV, e.g., FIV gp95 and/or gp36 protein, or whole FIV virus, or FIV-infected cells. Other immunization protocols with the vaccine compositions of the invention are apparent to persons skilled in the art and are contemplated within the scope of the present invention.

In one embodiment, immunogens from various primate immunodeficiency viral proteins are combined for administration to an animal. In an exemplified embodiment, a composition comprising an immunogen of HIV-1 p24 and an immunogen of HIV-1 gp120 and gp160 is administered to a feline animal. In another exemplified embodiment, a composition comprising HIV-1 p24 as the only immunogen is administered to a feline animal.

The subject invention also concerns materials and methods for protecting a feline animal against infection by an FIV or for generating an immune response against an FIV by administering to the animal a composition comprising immunogens derived from primate immunodeficiency viruses and immunogens derived from FIV. FIV-derived immunogens have been described in the art. See, for example, U.S. Pat. Nos. 5,118,602; 5,565,319; 5,510,106; 5,275,813; 5,037,753; and 4,861,720. FIV immunogens that can be used in accordance with the subject invention can be either of a single subtype or strain of FIV, or the immunogen can be derived from multiple subtypes of FIV. Multi-subtype FIV immunogens have been described in U.S. Pat. Nos. 5,846,825; 6,254,872; and 6,447,993.

In one embodiment of the subject methods, the immunogen to be administered to a feline animal comprises an epitope that is conserved between the primate immunodeficiency virus and FIV. In a further embodiment, the conserved epitope is present in the envelope protein of an immunodeficiency virus. Also contemplated within the scope of the invention are molecules (mimotope) which have a conformation that has a topology equivalent to a conserved epitope of the present invention and which binds to the same antigen-binding region of an antibody that binds to the conserved epitope. Typically, mimotopes are peptide molecules, but mimotopes can also be prepared from other non-peptide molecules.

The subject invention also concerns immunogens derived from a primate immunodeficiency virus, wherein the immunogen is a protein or peptide and comprises an epitope conserved between the primate immunodeficiency virus and FIV. In an exemplified embodiment, the immunogen comprises a gp120 and gp160 protein from HIV-1_(IIIB), and, optionally, a p24 protein from HIV_(UCD1). In another embodiment, the immunogen comprises a p24 protein from HIV_(UCD1). The subject invention also concerns polynucleotides that encode the protein or peptides comprising conserved epitopes of the immunodeficiency virus derived immunogens.

The subject invention also concerns antibodies that cross-react with epitopes of the immunogens derived from primate immunodeficiency viruses and FIV. The antibodies can be polyclonal or monoclonal in form. The antibodies can be derived from any animal capable of producing antibodies to the epitopes, and include, for example, human, ape, monkey, mouse, rat, goat, sheep, pig, cow, and feline animals. Also contemplated within the scope of the invention are non-human antibodies that cross-react with an epitope of the immunogen derived from a primate immunodeficiency virus and FIV but that have been “humanized” using standard procedures known in the art, such as those described in U.S. Pat. Nos. 5,530,101; 5,585,089; 5,693,762; 6,180,370; and 6,407,213.

Peptide and/or polypeptide immunogens of the present invention can also be provided in the form of a multiple antigenic peptide (MAP) construct. The preparation of MAP constructs has been described in Tam (1988). MAP constructs utilize a core matrix of lysine residues onto which multiple copies of an immunogen are synthesized (Posnett et al., 1988). Multiple MAP constructs, each containing the same or different immunogens, can be prepared and administered in a vaccine composition in accordance with methods of the present invention. In one embodiment, a MAP construct is provided with and/or administered with one or more adjuvants.

Natural, recombinant or synthetic polypeptides of primate immunodeficiency viral proteins, and peptide fragments thereof, can also be used as vaccine compositions according to the subject methods. In one embodiment, different polypeptides are administered as a combined preparation to a feline animal. In an exemplified embodiment, HIV-1 gp120/160 and HIV-1 p24 polypeptides are administered to a feline animal. In another embodiment, HIV polypeptides derived from more than one HIV strain are combined in a vaccine composition and are used to vaccinate a host animal. For example, polypeptides based on the HIV envelope glycoprotein from at least two strains of HIV-1 can be combined in the vaccine. The polypeptides may comprise “hybrid” or “chimeric” polypeptides whose amino acid sequence is derived from joining or linking polypeptides from at least two distinct HIV strains. Procedures for preparing HIV polypeptides are well known in the art. For example, HIV polypeptides can be synthesized using solid-phase synthesis methods (Merrifield, 1963). HIV polypeptides can also be produced using recombinant DNA techniques wherein a polynucleotide molecule encoding an HIV protein or peptide is expressed in a host cell, such as bacteria, yeast, or mammalian cell lines, and the expressed protein purified using standard techniques of the art.

According to the methods of the subject invention, the immunogenic compositions described herein are administered to susceptible hosts, typically domestic cats, in an effective amount and manner to induce protective immunity against subsequent challenge or infection of the host by FIV. The immunogens are typically administered parenterally, by injection, for example, either subcutaneously, intraperitoneally, or intramuscularly, or by oral or nasal administration, or any combination of such routes of administration. Usually, the immunogens are administered to a host animal at least two times, with an interval of one or more weeks between each administration. However, other regimens for the initial and booster administrations of the immunogens are contemplated, and may depend on the judgment of the practitioner and the particular host animal being treated.

Immunogens that can be used in accordance with the present invention can be provided with a pharmaceutically-acceptable carrier or diluent. Compounds and compositions useful in the subject invention can be formulated according to known methods for preparing pharmaceutically useful compositions. Formulations are described in detail in a number of sources which are well known and readily available to those skilled in the art. For example, Remington's Pharmaceutical Science by E. W. Martin, Easton Pa., Mack Publishing Company, 19^(th) ed., 1995, describes formulations which can be used in connection with the subject invention. In general, the compositions of the subject invention will be formulated such that an effective amount of an immunogen is combined with a suitable carrier in order to facilitate effective administration of the composition. The compositions used in the present methods can also be in a variety of forms. These include, for example, solid, semi-solid, and liquid dosage forms, such as tablets, pills, powders, liquid solutions or suspension, suppositories, injectable and infusible solutions, and sprays. The preferred form depends on the intended mode of administration and therapeutic application. The compositions also preferably include conventional pharmaceutically acceptable carriers and diluents which are known to those skilled in the art. Examples of carriers or diluents for use with the subject peptidomimetics include, but are not limited to, water, saline, oils including mineral oil, ethanol, dimethyl sulfoxide, gelatin, cyclodextrans, magnesium stearate, dextrose, cellulose, sugars, calcium carbonate, glycerol, alumina, starch, and equivalent carriers and diluents, or mixtures of any of these. Formulations of an immunogen of the invention can also comprise suspension agents, protectants, lubricants, buffers, preservatives, and stabilizers. To provide for the administration of such dosages for the desired therapeutic treatment, pharmaceutical compositions of the invention will advantageously comprise between about 0.1% and 45%, and especially, 1 and 15% by weight of the immunogen or immunogens based on the weight of the total composition including carrier or diluent.

The immunogenic compositions of the subject invention can be prepared by procedures well known in the art. For example, the immunogens are typically prepared as injectables, e.g., liquid solutions or suspensions. The immunogens are administered in a manner that is compatible with dosage formulation, and in such amount as will be therapeutically effective and immunogenic in the recipient. The optimal dosages and administration patterns for a particular immunogens formulation can be readily determined by a person skilled in the art.

As noted above, virus and cells in a immunogenic formulation may be inactivated or attenuated using methods known in the art. The amount of cell-free whole or partial virus in a vaccine dose will usually be in the range from about 0.1 mg to about 5 mg, and more usually being from about 0.2 mg to about 2 mg. The dosage for formulations comprising virus-infected cell lines will usually contain from about 10⁶ to about 10⁸ cells per dose, and more usually from about 5×10⁶ to about 7.5×10⁷ cells per dose. The amount of protein or peptide immunogen in a dose for a feline animal can vary from about 0.1 μg to 10000 μg, or about 1 μg to 5000 μg, or about 10 μg to 1000 μg, or about 25 μg to 750 μg, or about 50 μg to 500 μg, or 100 μg to 250 μg, depending upon the size, age, etc., of the animal receiving the dose.

In one embodiment, an immunogen of the invention is provided with one or more adjuvants that increase the animal's immune response against the immunogen. Immunogens of the invention can be provided with and/or administered with any suitable adjuvant or adjuvants known in the art. Adjuvants that can be used in the immunogen formulations of the invention include threonyl muramyl dipeptide (MDP) (Byars et al., 1987), Ribi adjuvant system components (Corixa Corp., Seattle, Wash.) including the cell wall skeleton (CWS) component, Freund's complete, and Freund's incomplete adjuvants or a combination thereof. A variety of other adjuvants suitable for use with the methods and vaccines of the subject invention, such as alum, aluminum hydroxide, and saponin are well known in the art and are contemplated for use with the subject invention. Cytokines (γ-IFN, GM-CSF, CSF, etc.) and lymphokines (IL-1, IL-2, etc.) have also been used as adjuvants and/or supplements to vaccine compositions and are contemplated within the scope of the present invention. One or more different cytokines and lymphokines can be included in a composition comprising an immunogen of the invention. In one embodiment, an immunogen of the invention is administered to an animal in combination with the lymphokine interleukin-12 (IL-12) in combination with another adjuvant. Also specifically contemplated within the scope of the invention is the use of the lymphokine interleukin-18 (IL-18) as part of an adjuvant composition. In one embodiment, an adjuvant composition used with the subject invention comprises a combination of IL-12 and IL-15, or IL-15 and IL-18, or IL-12 and IL-18, or IL-12, IL-15, and IL-18. Preferably, the cytokine is of a species that has biological activity in the feline animal. More preferably, the cytokine is a feline cytokine, e.g., feline IL-12, feline IL-15, feline IL-18, etc. In an exemplified embodiment, a primate derived immunogen is administered in combination with Ribi adjuvant system component including CWS and IL-12 and/or IL-18.

Abbreviations of FIV strains used herein are shown below: Strain (subtype) Abbreviation Petaluma (A) FIV_(Pet) Dixon (A) FIV_(Dix) UK8 (A) FIV_(UK8) Bangston (B) FIV_(Bang) Aomori-1 (B) FIV_(Aom1) Aomori-2 (B) FIV_(Aom2) Fc1 (B) FIV_(FC1) Shizuoka (D) FIV_(Shi) Dutch113 (A) FIV_(Dut113) Dutch19K (A) FIV_(Dut19) UK2 (A) FIV_(UK2) SwissZ2 (A) FIV_(SwiZ2) Sendai-1 (A) FIV_(Sen1) Sendai-2 (B) FIV_(Sen2) USCAzepy01A (A) FIV USCAhnky11A (A) FIV_(USC11) USCAtt-10A (A) FIV_(USC10) USCAlemy01 (A) FIV USCAsam-01A (A) FIV PPR (A) FIV_(PPR) FranceWo FIV_(Fra) Netherlands FIV_(Net) USILbrny03B (B) FIV_(USI03) TM2 (B) FIV_(TM2) USCKlgri02B (B) FIV_(USC02) Yokohama (B) FIV_(Yok) USMAsboy03B (B) FIV_(USMA03) USTXmtex03B (B) FIV_(UST03) USMCglwd03B (B) FIV_(USMC03) CABCpbar03C (C) FIV_(CAB03) CABCpbar07C (C) FIV_(CAB07) CABCpady02C (C) FIV_(CAB02) Fukuoka (D) FIV_(Fuku)

The subject invention also concerns methods of use of an animal model for selecting for epitopes conserved between immunodeficiency viruses, such as HIV and FIV, that can be used to immunize a person or animal against infection by an immunodeficiency virus. In one embodiment of the method, HIV is isolated from an HIV-infected, long-term nonprogressor patient. As used herein, the term “long-term nonprogressors” refers to HIV-infected patients that exhibit a stable CD4 count for at least 10 years, exhibit a low virus load (i.e., virus level in plasma is low to undetectable as measured by RT-PCR) and typically exhibit few or no disease symptoms. Immunogens from the isolated HIV are prepared and used to immunize a feline animal, such as a domestic cat. In one embodiment of the method, peptide fragments of an HIV protein are used as immunogens. Preferably, overlapping fragments that represent the full length of the HIV protein are prepared for use as immunogens. In one embodiment, different combinations of the peptide fragments are administered to different cats in order to identify those fragments that contain epitopes that provide the strongest prophylactic protection against FIV infection. Immunized cats are subsequently challenged with FIV. Immunogens that protect a cat against infection when challenged with FIV comprise evolutionarily conserved epitopes and can be used as immunogens to immunize humans, feline animals, and other mammals against infection by immunodeficiency viruses. Preferably, the immunogen protects a cat against infection by FIV of more than one subtype. Fragments of an immunogen comprising an evoluationarily conserved epitope can be prepared and tested using the subject method to further isolate the epitope. Fragments can also be sequenced to determine the primary amino acid sequence of the epitope. In a preferred embodiment, an immunogen comprising an evolutionarily conserved epitope selected using the subject method can be used to immunize a human against infection from HIV. In one embodiment of the method, the immunogen used to immunize cats is an HIV p24 protein, or an immunogenic fragment thereof. The subject invention also concerns evolutionarily conserved epitopes of immunodeficiency viruses identified using the subject method.

The subject invention also concerns methods for inducing an immune response in humans and other animals against immunogens, antigens, or viruses comprising epitopes that are evolutionarily conserved among immunodeficiency viruses, such as HIV and FIV. In one embodiment, an immunogen(s) or antigen(s) comprising one or more evolutionarily conserved epitope(s) from an immunodeficiency virus(es) identified by methods described herein is administered to a person or animal in an amount and for a duration sufficient to induce an immune response against the immunogen or antigen and any virus or cell displaying the immunogen or antigen. The immune response induced can be humoral or cell-mediated or both. In one embodiment for inducing an immune response against HIV, a human is administered an immunogen comprising an evolutionarily conserved epitope identified from an HIV. Immunogens contemplated within the scope of the invention include, but are not limited to, an HIV p24 protein, or an immunogenic fragment thereof. In one embodiment, an immunogen used in the present method comprises an HIV-1_(UCD1) p24 protein, or an immunogenic fragment thereof.

The subject invention also concerns methods for protecting humans, and other animals, such as cats, against infection by immunodeficiency viruses, such as HIV and FIV. In one embodiment of the method, an effective amount of an immunogen(s) or antigen(s) comprising one or more evolutionarily conserved epitope(s) from an immunodeficiency virus(es) identified by methods described herein is administered to a person or animal for a duration sufficient to immunize a person or animal and provide the person or animal with some level of protection against infection by an immunodeficiency virus. In one embodiment for protection against HIV infection, a human is immunized with an immunogen comprising an evolutionarily conserved epitope identified from an HIV. Immunogens contemplated within the scope of the invention include, but are not limited to, an HIV p24 protein, or an immunogenic fragment thereof. In one embodiment, an immunogen used in the present method comprises an HIV-1_(UCD1) p24 protein, or an immunogenic fragment thereof.

The immunogens are typically administered parenterally, by injection, for example, either subcutaneously, intraperitoneally, or intramuscularly. Other suitable modes of administration include oral or nasal administration. Usually, the immunogens are administered to a human or other animal at least two times, with an interval of one or more weeks between each administration. However, other regimens for the initial and booster administrations of the immunogens are contemplated, and may depend on the judgment of the practitioner and the patient being treated.

The immunogenic compositions of the subject invention can be prepared by procedures well known in the art. For example, the immunogens are typically prepared as injectables, e.g., liquid solutions or suspensions. The immunogens are administered in a manner that is compatible with dosage formulation, and in such amount as will be therapeutically effective and immunogenic in the recipient. The optimal dosages and administration patterns for a particular immunogens formulation can be readily determined by a person skilled in the art.

Immunogens that can be used in accordance with the present invention can be provided with a pharmaceutically-acceptable carrier or diluent. In one embodiment, an immunogen of the invention is provided with one or more adjuvants that increase the human or animal's immune response against the immunogen. Immunogens of the invention can be provided with and/or administered with any suitable adjuvant or adjuvants known in the art.

The subject invention also concerns compositions comprising an immunogen of the invention derived from a primate immunodeficiency virus and a feline cytokine or lymphokine. The immunogen can be from HIV, including HIV-1, e.g., HIV-1_(IIIB), HIV-1_(UCD1), and HIV-1_(BRU), and HIV-2. HIV immunogens of the composition include, but are not limited to, HIV gp160, gp120, gp41, p24, p31, p17, p7 or a protein encoded by an HIV gag, pol, env, tat, rev, nef, vif, vpr, vpu, or vpx genes, or a fragment or variant thereof. In one embodiment, the lymphokine is feline IL-12, IL-15, and or IL-18. In an exemplified embodiment, the immunogen is HIV-1 p24 and the lymphokine is feline IL-18. Compositions can also include an adjuvant, such as one of the adjuvants described herein.

The subject invention also concerns kits and dosage formulations comprising in one or more containers an immunogen of the invention derived from a primate immunodeficiency virus and a feline cytokine or lymphokine. The immunogen can be from HIV, including HIV-1, e.g., HIV-1_(IIIB), HIV-1_(UCD1), and HIV-1_(BRU), and HIV-2. HIV immunogens of the composition include, but are not limited to, HIV gp160, gp120, gp41, p24, p31, or a protein encoded by an HIV gag, pol, env, tat, rev, nef, vif, vpr, vpu, or vpx gene, or a fragment or variant thereof. In one embodiment, the lymphokine is feline IL-12, IL-15, and or IL-18. In an exemplified embodiment, the immunogen is HIV-1 p24 and the lymphokine is feline IL-1 8. Kits and dosage formulations can also include an adjuvant, such as one of the adjuvants described herein.

All patents, patent applications, provisional applications, and publications referred to or cited herein are incorporated by reference in their entirety to the extent they are not inconsistent with the explicit teachings of this specification.

Following are examples which illustrate procedures for practicing the subject invention. These examples should not be construed as limiting. All percentages are by weight and all solvent mixture proportions are by volume unless otherwise noted.

EXAMPLE 1

Four SPF cats each (n=4) were immunized four times with either HIV-1 vaccine formulation A or HIV-1 vaccine formulation B at 3 week intervals and challenged 3 weeks after the last boost with 15 cat infectious doses (CID₅₀) of in vivo-derived FIV_(Bangston) innoculum. Additional four SPF cats (control group) received no immunization but were similarly challenged with FIV. HIV-1 vaccine formulation A consisted of 200 μg of HIV-1_(UCD1) p24, 25 μg of HIV-1_(IIIB) gp120 (ImmunoDiagnostics Inc., Woburn, Mass.), and 25 μg of HIV-1_(IIIB) gp160 (ImmunoDiagnostics Inc.) mixed in 0.5 ml of Ribi Adjuvant System comprising the cell wall skeleton (CWS) component (25 μg/dose cell wall skeleton)(Corixa Corp., Seattle, Wash.) containing 5 μg of recombinant human interleukin-12 (rHuIL-12). HIV-1 vaccine formulation B consisted of 200 μg of HIV-1_(UCD1) p24 mixed in 0.5 ml of Ribi Adjuvant System CWS component containing 5 μg of rHuIL-12. Recombinant HIV-1_(UCD1) p24 was produced in an E. coli expression system using QIAexpress pQE vector (Qiagen Inc., Valencia, Calif.) and the expressed 6xHis-tagged p24 product was purified by Ni-NTA affinity chromatography (Qiagen Inc.). In vivo-derived FIV innoculum consisted of pooled plasma from two FIV_(Bangston)-infected cats which was titrated in vivo using groups of 3-4 SPF cats per log₁₀ dilution (Pu et al., 2001).

Results of this study are shown in Table 1. As an additional method of determining FIV infection status, virus isolation was performed using both reverse transcriptase (RT) assay with proviral PCR as virus detection systems. One of four (1/4) cats immunized with HIV-1 vaccine formulation A and two of four (2/4) cats immunized with HIV-1 vaccine formulation B and subsequently challenged with FIV were negative for FIV by virus isolate, lost antibodies to FIV p24 and developed no antibodies to FIV gp95 at 16 weeks post challenge, while the remaining cats developed antibodies to FIV gp95 and developed persistently stronger antibody responses to FIV p24. All four control cats developed antibodies to both FIV p24 and gp95 by 16 weeks post challenge and virus isolation positive for FIV by 13 weeks post challenge. Hence, HIV-1 vaccine formulation B (HIV-1 p24 alone) appeared to have better or equivalent efficacy at protecting cats against FIV challenge than HIV-1 vaccine formulation A, suggesting that HIV-1_(UCD1) p24 is a vaccine component that can induce protective immunity against FIV challenge. All four cats immunized with HIV-1 vaccine formulation A and three of four cats immunized with HIV-1 vaccine formulation B developed cross-reactive antibodies to FIV p24 after the fourth (4th) vaccination.

Since there were no cross-reactive antibodies to FIV gp95 in HIV-1 vaccinated cats that exhibited a protective immune response to FIV, the absence or presence of antibodies to FIV gp95 was indicative of whether an animal had been vaccinated with HIV or infected with FIV, respectively. In addition, the loss of cross-reactive antibodies to FIV p24 in vaccinated cats by the end of the study was also indicative that the vaccinated animals were protected from FIV challenge.

EXAMPLE 2

In a subsequent study, four specific-pathogen-free (SPF) cats were each immunized with either HIV-1/UCD1 (HIV-1_(UCD1)) p24 or HIV-1/LAV (HIV-1_(LAV)) p24 vaccines at 250 μg/dose in 1 ml of Ribi adjuvant (25 μg/dose CWS (cell wall skeleton)) supplemented with 5 μg/dose of recombinant human IL-12 (rHuIL-12). An additional group of three SPF cats received HIV-1_(UCD1) p24 without Ribi adjuvant or rHuIL-12 to evaluate the importance of adjuvant. A control group of cats received either Ribi adjuvant or PBS. All cats were immunized three (3) times at three (3) week intervals and challenged three (3) weeks after the last immunization with 15 CID₅₀ of in vivo-derived FIV-Bangston (FIV_(Bang)). As shown in Table 2, four of four (4/4) cats immunized with HIV-1_(UCD1) p24 with adjuvant were protected from FIV infection at a dose where all four control cats were infected with FIV following challenge. The protected cats immunized with HIV-1_(UCD1) p24 with adjuvant were negative for FIV infection as of 54 weeks post challenge and, therefore, they were completely protected. Results shown in Table 2 suggest that the HIV-1_(UCD1) p24 vaccine (4 of 4 cats or 100% protected) is more effective than the HIV-1_(LAV) p24 vaccine (2 of 4 cats or 50% protected). The group that received HIV-1_(UCD1) p24 without adjuvant had minimal protection from infection when challenged with FIV (1 of 3 cats or 33% protected).

EXAMPLE 3

Another study was performed to determine whether the protection induced by HIV-1_(LAV) p24 vaccine is reproducible. In this study, three SPF cats were immunized with 200 μg/dose of HIV-1_(LAV) p24 vaccine formulated in 1 ml of Ribi adjuvant (25 μg/dose CWS (cell wall skeleton)) supplemented with 5 μg/dose of rHuIL-12. In addition, three SPF cats each were immunized with 200 μg/dose of either FIV_(Bang) p24 or FIV-Petaluma+Shizuoka (FIV_(Pet/Shi)) p24 vaccines formulated in Ribi adjuvant (25 μg/dose CWS (cell wall skeleton)) with 5 μg/dose of rHuIL-12. FIV_(Pet/Shi) p24 vaccine consisted of 130 μg of FIV_(Pet p)24 and 70 μg of FIV_(Shi) p24 in Ribi adjuvant supplemented with rHuIL-12. Three control cats received adjuvant. Immunization and challenge schedules including challenge innoculum and dose were the same as described in Example 2. As shown in Table 3, three of three (3/3) cats immunized with HIV-1_(LAV) p24 vaccine were protected at a dose which infected all three control cats. Only 1 of 3 cats immunized with FIV_(Bang) p24 vaccine and 2 of 3 cats immunized FIV_(Pet/Shi) p24 vaccine were protected. These results confirm that the HIV-1_(LAV) p24 vaccine is also effective as vaccine against FIV. Moreover, the HIV-1 p24 vaccine is as effective as the FIV_(Pet/Shi) p24 vaccine and may be more effective than the FIV_(Bang) p24 vaccine against FIV_(Bang) challenge.

EXAMPLE 4

Another study was performed to evaluate the effect of lowering the p24 vaccine dose and changing the cytokine supplementation of the adjuvant. Three SPF cats were immunized with 200 μg/dose of HIV-1_(UCD1) p24 antigen formulated in 1 ml of Ribi adjuvant (25 μg/dose CWS (cell wall skeleton)) supplemented with recombinant feline IL-18 (rFeIL-18; 5 μg/dose) instead of rHuIL-12. In order to determine the effect of cytokine supplementation of the adjuvant, three additional SPF cats were immunized with 200 μg/dose of HIV-1_(UCD1) p24 antigen formulated in Ribi adjuvant (25 μg/dose CWS (cell wall skeleton)) with no cytokine supplementation. As controls, two SPF cats each were immunized with either Ribi adjuvant with supplemented rFeIL-18, Ribi adjuvant alone, or PBS. Immunization and challenge schedules were the same as described in Examples 2 and 3 with the exception of the slightly higher challenge dose of 25 CID₅₀. As shown in Table 4, two of three (2/3) cats immunized with HIV-1_(UCD1) p24 vaccine formulated in rFeIL-18 supplemented Ribi adjuvant were protected, whereas, only one of three (1/3) cats immunized HIV-1 p24 vaccine formulated with only Ribi adjuvant were protected. All control cats were infected by 5 to 9 weeks post challenge. Hence, protection (2 of 3 cats) was demonstrated with HIV-1_(UCD1) p24 vaccine formulated in Ribi/FeIL-18. Furthermore, HIV-1_(UCD1) p24 vaccine formulated in Ribi/FeIL-18 appeared to be more effective than the one formulated in only Ribi adjuvant (without FeIL-18) (2 of 3 protected cats vs. 1 of 3 protected cats).

EXAMPLE 5

In another study, the challenge strain was changed from FIV_(Bang) (which is subtype A/B) to FIV_(FC1) (which is subtype B) to test whether the HIV-1 p24 vaccine will protect cats against other FIV challenge strains. FIV_(Bang) has group-specific antigen (gag), polymerase (pol), and small portion (V1-V3 regions) of the envelope (env) gene sequences belonging to subtype A, while a majority of the env gene (V4-V9 regions) belongs to subtype B. Hence, FIV_(Bang) is a recombinant of subtypes A and B. On the other hand, FIV_(FC1) has subtype B gene sequences at gag, pol, and env, and is completely a subtype B strain. The gag consists of matrix-core-nucleocapsid and the core gene is the gene for p24. Thus, HIV-1_(UCD1) and HIV-1_(LAV) p24 vaccines protected cats against FIV_(Bang), which has a subtype A p24. This study tested whether the HIV-1 p24 vaccine protects cats against infection by FIV_(FC1) which has a subtype B p24.

Four SPF cats were immunized with 200 mg/dose of HIV-1_(UCD1) p24 in 1 ml of Ribi adjuvant (25 μg/dose CWS (cell wall skeleton)) supplemented with 5 μg/dose of rHuIL-12. For comparison, an additional four (4) SPF cats were immunized with a commercially available dual-subtype FIV_(Pet/Shi) vaccine (FEL-O-VAX FIV; Forth Dodge Animal Health, Overland Park, Kans.) in the adjuvant supplied with the vaccine. Three control cats received immunization with PBS. The immunization and challenge schedules were the same as described in Examples 2 and 3 with the exception of the challenge inoculum of FIV_(FC1) was 15 CID₅₀. As shown in the results in Table 5, three of four (3/4) cats immunized with HIV-1_(UCD1) p24 vaccine and all four FEL-O-VAX FIV-immunized cats were protected at a dose where all three control cats were infected. Hence, HIV-1 p24 vaccine protected cats against a challenge strain (FIV_(FC1)), which had subtype B p24 and is significantly different from the FIV_(Bang) challenge strain.

EXAMPLE 6

The results from the studies described in Example 1 through Example 5 are summarized in Table 6. Overall, 11 of 15 (73.3%) cats immunized with HIV-1_(UCD1) p24 formulated in Ribi/rHuIL-12 or Ribi/rFeIL-18 adjuvant were protected. Similarly, 5 of 7 (71.4%) cats immunized with HIV-1_(LAV) p24 formulated in Ribi/rHuIL-12 were protected. Initial analysis of immunization with HIV-1 p24 formulated with only Ribi/rHuIL-12 indicate that HIV-1_(UCD1) p24 vaccine (7 of 8 protected cats or 87% protection) may be more effective than HIV-1_(LAV) p24 vaccine (5 of 7 protected cats or 71% protection). Nonetheless, full sterilizing protection was observed in a combined total of 16 of 22 (72.7%) cats immunized with HIV-1 p24 vaccines in Ribi/rHuIL-12 or Ribi/rFeIL-18, which was substantially higher in protection than the 3 of 6 (50%) cats protected after immunization with FIV p24 vaccine.

It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and the scope of the appended claims. TABLE 1 HIV-1 Protein Immunogenicity & Efficacy Against FIV_(Bang) Challenge Infection (Study 1) HIV-1 Immu- noblot VACCINE: (p24/ FIV HIV-1 gp120/ FIV Status Status Immunogens FIV Immunoblot (p24/gp95) 160) (Virus Isolation) Sum- Cat # (Adjuvants) Pre V3 V4 4 wpc 7 wpc 10 wpc 13 wpc 16 wpc Pre V4 10 wpc 13 wpc 16 wpc 18 wpc mary Formulation A: L99 HIV-1_(UCD1) −/− −/H +/H ±/H +/− +/− +/− +/+ −/− +/+ + + + + + 808 p24 + −/− ++/H ++/H +/H +/− +/− +/− +/+ −/− +/+ + + + + + 9QM HIV-1_(IIIB) −/− +/H +/H ±/− −/− −/− −/− −/− −/− +/+ − − − − − 902 gp120/160 −/− +/H ++/H +/H +/− +/− +/− +/+ −/− +/+ + + + + + (Ribi + IL-12) Formulation B: K99 HIV-1_(UCD1) p24 −/− −/− −/− −/− −/− −/− −/− −/− −/− +/− − − − − − 806 (Ribi + IL-12) −/− −/− +/− ±/− +/− +/− +/− +/+ −/− +/− + + + + + 9QL −/− +/− +/− +/− −/− −/− −/− −/− −/− +/− − − − − − 901 −/− −/− +/− +/− ±/− +/− +/− +/+ −/− +/− + + + + + M99 None −/− −/− −/− +/− +/− +/− +/− +/+ −/− ND + + + + + 811 −/− −/− −/− +/− +/− +/− +/± +/+ −/− ND + + + + + 9QN −/− −/− −/− ±/− +/− ±/− ±/− +/+ −/− ND − + + + + 6DJ −/− −/− −/− +/+ ±/− +/+ +/+ +/+ −/− ND + + + + + Pre = pre-vaccination; V3 = post-3rd vaccination; V4 = post-4th vaccination. 4, 7, 10, 13, 16 & 18 wpc = 4, 7, 10, 13, 16 and 18 weeks post-challenge with FIV. Negative (−/−) for antibodies to core p24 and envelope (FIV gp95; HIV gp120/160). Positive for p24 antibodies but not for envelope antibodies (+/−). Positive (+/+) for antibodies to core p24 and envelope. H = antibodies to high molecular weight (p70) protein but no antibodies to FIV envelope (gp95). ND = not determined

TABLE 2 HIV-1 Protein Immunogenicity (3X Immunization) & Efficacy Against Subtype-A/B FIV_(Bang) Challenge Infection (15 CID₅₀) (Study 2) VACCINE: FIV Status HIV-1 FIV Immunoblot (p24/gp95) (Virus Isolation) FIV Immunogens 4 6 9 12 16 Status Cat # (Adjuvants) Pre V3 wpc wpc wpc 12 wpc 16 wpc 20 wpc 4 wpc 6 wpc 9 wpc wpc wpc 20/54 wpc Summary G9F HIV-1_(UCD1) p24 −/− +/− +/− ±/− −/− −/− −/− −/− − − − − − −/− − P99 250 μg/dose −/− +/− +/− ±/− −/− −/− −/− −/− − − − − − −/− − 93M (Ribi + IL-12) −/− +/− +/− ±/− −/− −/− −/− −/− − − − − − −/− − 400 −/− +/− +/− ±/− −/− −/− −/− −/− − − − − − −/− − R99 HIV-1_(LAV) p24 −/− +/− +/− ±/− −/− −/− −/− −/− − − − − − −/− − 93P 250 μg/dose −/− +/− +/− ±/− +/− +/+ +/+ +/+ − + + + + +/T + DE1 (Ribi + IL-12) −/− +/− +/− ±/− +/− +/+ +/+ +/+ + + + + + +/T + 099 −/− +/− +/− −/− −/− −/− −/− −/− − − − − − −/− − S99 HIV-1_(UCD1) p24 −/− −/− −/− +/− +/− +/+ +/+ +/+ − − + + + +/T + 206 250 μg/dose −/− −/− −/− −/− −/− +/− +/+ +/+ − − − + + +/T + MN1 (No Adjuvant) −/− −/− −/− −/− −/− −/− −/− −/− − − − − − −/− − G9H (Ribi or PBS) −/− −/− −/− +/− +/− +/+ +/+ +/+ − + + + + +/T + N99 −/− −/− −/− +/− +/− +/+ +/+ +/+ + + + + + +/T + G9E −/− −/− −/− −/− −/− +/− +/+ +/+ − − − + + +/T + NN1 −/− −/− −/− −/− −/− −/− +/± +/+ − − − − + +/T + Pre = pre-vaccination; V3 = post-3rd vaccination; 4, 6, 9, 16, 20, 48, and 54 wpc = 4, 6, 9, 16, 20, 48, and 54 wk post-challenge with in vivo inoculum (pooled infected plasma) of FIV-Bang (subtype A/B). Ribi + IL-12 consist of Ribi adjuvant with 25 μg/dose cell wall skeleton and 5 μg of human IL-12 per dose. FIV immunoblot negative (−/−) for antibodies to core p24 and envelope (FIV gp95) indicates still negative for FIV infection. FIV immunoblot positive for p24 antibodies but not for envelope antibodies (+/−). The vaccinated cat may be still negative for virus infection unless the anti-p24 antibody titer is stronger than # previous titer. However, for PBS controls, such immunoblot reactivity will indicate FIV infection. FIV immunoblot positive (+/+) for antibodies to core p24 and envelope indicates positive for FIV infection in both vaccinated groups and PBS control group. FIV virus isolation negative (−) and positive (+) were based on RT and PCR. FIV virus isolation negative at 20/54 wpc (−/−) represent isolation performed at 20 wpc and 54 wpc. These animals are still alive and will be used for 1-yr boost-challenge study. FIV virus isolation positive at 20 wpc but not tested at 48 wpc due # to euthanasia of these animals after harvesting the tissues on 20 wpc (+/T).

TABLE 3 HIV-1 & FIV p24 Protein Immunogenicity (3x Immunization) & Efficacy Against Subtype-A/B FIV_(Bang) Challenge Infection (15 CID₅₀) (Study 3) VACCINE: FIV Status HIV-1 FIV Immunoblot (p24/gp95) (Virus Isolation) FIV Immunogens 5 8 10 12 15 Status Cat # (Adjuvants) Pre V3 wpc wpc wpc 12 wpc 15 wpc 18 wpc 5 wpc 8 wpc 10 wpc wpc wpc 18 wpc Summary 626 HIV-1_(LAV) p24 −/− +/− +/− −/− −/− −/− −/− −/− − − − − − −/− − 637 200 μg/dose −/− +/− +/− −/− −/− −/− ND ND − − − − ND ND − ID4 (Ribi + IL-12) −/− +/− +/− −/− −/− −/− −/− −/− − − − − − −/− − 628 None −/− −/− −/− −/− −/− +/+ +/+ +/+ − − − − + + + 633 (Ribi/IL-12) −/− −/− −/− −/− −/− +/+ +/+ +/+ − − − − + + + ID2 −/− −/− −/− −/− −/− +/+ +/+ +/+ + + + + + + + 631 FIV_(Bang) p24 −/− +/− +/− +/− +/− +/− +/− +/− − − − − − − − 635 200 μg/dose −/− +/− +/− +/− +/− +/+ +/+ +/+ − − − + − + + ID3 (Ribi + IL-12) −/− +/− +/− +/− +/− +/+ +/+ +/+ + + + + + + + 630 FIV_(Pet/Shi) p24 −/− +/− +/− +/− +/− +/− +/− +/− − − − − − − − ID1 200 μg/dose −/− +/− +/− +/− +/− +/+ +/+ +/+ + + + + + + + G9B (Ribi + IL-12) −/− +/− +/− +/− +/− +/− +/− +/− − − − − − − − Pre = pre-vaccination; V3 = post-3rd vaccination; 5, 8, 10, 12, 15, and 18 wpc = 5, 8, 10, 12, 15, 18 wk post-challenge with in vivo inoculum (pooled infected plasma) of FIV-Bang. Ribi + IL-12 consist of Ribi adjuvant with 25 μg/dose cell wall skeleton and μg of human IL-12 per dose. FIV immunoblot negative (−/−) for antibodies to core p24 and envelope (FIV gp95) indicates still negative for FIV infection. FIV immunoblot positive for p24 antibodies but not for envelope antibodies (+/−). The vaccinated cat may be still negative for virus infection unless the anti-p24 antibody # titer is stronger than previous titer. However, for PBS controls, such immunoblot reactivity will indicate FIV infection. FIV immunoblot positive (+/+) for antibodies to core p24 and envelope indicates positive for FIV infection in both vaccinated groups and PBS control group. FIV virus isolation negative (−) and positive (+) were based on RT and PCR. FIV immunoblot and virus isolation missing (ND = not done) for cat #637 due to accidental death after harvesting samples caused by reaction to anesthesia.

TABLE 4 HIV-1 p24 Protein Immunogenicity (3x Immunization & FeIL-18 adjuvant) & Efficacy Against subtype-A/B FIV_(Bang) Challenge (25 CID₅₀)(Study 4) VACCINE: HIV-1 FIV Status FIV Immunogens FIV Immunoblot (p24/gp95) (Virus Isolation) Status Cat # (Adjuvants) Pre V3 5 wpc 7 wpc 9 wpc 12-19 wpc 5 wpc 7 wpc 9 wpc 12-19 wpc Summary IZ1 HIV-1_(UCD1) p24 −/− +/− +/− −/− +/− +/+ + + + + + JB6 200 μg/dose −/− +/− +/− −/− −/− −/− − − − − − IW1 (Ribi + FeIL-18) −/− +/− +/− −/− −/− −/− − − − − − IZ3 HIV-1_(UCD1) p24 −/− +/− +/− −/− −/− −/− − − − − − JB5 200 μg/dose −/− +/− +/− +/− +/− +/+ + + + + + JA1 (Ribi) −/− +/− +/− +/− +/− +/+ + + + + + IZ6 None −/− −/− −/− −/− +/− +/+ − − + + + JB2 (Ribi + FeIL- −/− −/− +/− +/− +/− +/+ + + + + + IW2 18 or Ribi) −/− −/− −/− +/− +/− +/+ − + + + + JJ4 −/− −/− −/− −/− +/− +/+ − − + + + JB1 None −/− −/− −/− −/− +/− +/+ − − + + + MK2 (PBS) −/− −/− −/− −/− +/− +/+ − − + + + Pre = pre-vaccination; V3 = post-3rd vaccination; 5, 7, 9, and 12 wpc = 5, 7, 9, 12, 16, and 19 wk post-challenge with in vivo inoculum (pooled infected plasma) of FIV-Bang. Ribi + FeIL-18 consist of Ribi adjuvant with 25 μg/dosecell wall skeleton and 5 μg of feline IL-18 per dose. FIV immunoblot negative (−/−) for antibodies to core p24 and envelope (FIV gp95) indicates still negative for FIV infection. FIV immunoblot positive for p24 antibodies but not for envelope antibodies (+/−). The vaccinated cat may be still negative for virus infection unless the anti-p24 antibody titer is stronger than previous titer. However, for PBS controls, such immunoblot reactivity will indicate FIV infection. FIN immunoblot positive (+/+) for antibodies to core p24 and envelope indicates positive for FIN infection in both vaccinated groups and PBS control group. FIV virus isolation negative (−) and positive (+) were based on RT and PCR.

TABLE 5 HIV-1 p24 Protein Immunogenicity (3x Immunization) & Efficacy Against subtype-B FIV_(FC1) Challenge Infection (15 CID₅₀) (Study 5) VACCINE: HIV-1 FIV Status FIV Immunogens FIV Immunoblot (p24/gp95) (Virus Isolation) Status Cat # (Adjuvants) Pre V3 5 wpc 7 wpc 9 wpc 12-16 wpc 5 wpc 7 wpc 9 wpc 12-16 wpc Summary AA1 HIV-1_(UCD1) p24 −/− +/− +/− −/− +/− +/+ − + + + + MD1 200 μg/dose −/− +/− +/− −/− −/− −/− − − − − − MG1 (Ribi + IL-12) −/− +/− +/− −/− −/− −/− − − − − − MF3 −/− +/− +/− −/− −/− −/− − − − − − AA2 Fel-O-Vax FIV_(Pet/Shi) −/− +/+ +/± +/± +/± +/± − − − − − MD2 Fort Dodge adjuvant −/− +/+ +/± +/± +/± +/± − − − − − MG2 −/− +/+ +/± +/± +/± +/± − − − − − MF4 +/+ +/± +/± +/± +/± − − − − − MD3 None −/− −/− −/− −/− +/− +/+ − − − + + MG5 (PBS) −/− −/− −/− −/− +/− +/+ − − + + + MK4 −/− −/− −/− −/− +/− +/+ − − + + + Pre = pre-vaccination; V3 = post-3rd vaccination; 5, 7, 9, and 12 wpc = 5, 7, 9, 12, and 16 wk post-challenge with in vivo inoculum (pooled infected plasma) of FIV-FC1 (subtype B). Ribi + IL-12 consist of Ribi adjuvant with 25 μg/dose cell wall skeleton and 5 μg of human IL-12 per dose. FIV immunoblot negative (−/−) for antibodies to core p24 and envelope (FIV gp95) indicates still negative for FTV infection. FIV immunoblot positive for p24 antibodies but not for envelope antibodies (+/−). The vaccinated cat may be still negative for virus infection unless the anti-p24 antibody titer is stronger than previous titer. However, for PBS controls, such immunoblot reactivity will indicate FIV infection. FIV immunoblot positive (+/±) for antibodies to core p24 and envelope indicates antibodies from vaccine in Fel-O-Vax FIV group and these cats are not infected. FIV immunoblot positive (+/+) for antibodies to core p24 and envelope indicates positive for FIV infection in both vaccinated groups and PBS control group. FIV virus isolation negative (−) and positive (+) were based on RT and PCR.

TABLE 6 Summary Table Vaccination Protection Rate Individual Combined p24 Vaccine Adjuvant Frequency (reference Table) Protection Rate Protection Rate HIV-1/UCD1 p24 Ribi + IL-12 3X 4/4 (Table 2) 7/8 (87%) 11/15 (73%) 3/4 (Table 5) HIV-1/UCD1 p24 Ribi + IL-12 4X 2/4 (Table 1) 2/4 (50%) HIV-1/UCD1 p24 Ribi + FeIL-18 3X 2/3 (Table 4) 2/3 (67%) HIV-1/LAV p24 Ribi + IL12 3X 2/4 (Table 2) 5/7 (71%)  5/7 (71%) 3/3 (Table 3) FIV-Bang p24 Ribi + IL-12 3X 1/3 (Table 3) 1/3 (33%)  3/6 (50%) FIV-Pet/Shi p24 Ribi + IL-12 3X 2/3 (Table 3) 2/3 (67%)

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1. A method for inhibiting or preventing infection by feline immunodeficiency virus (FIV) in a feline animal, said method comprising administering to said animal an effective amount of an immunogen derived from a primate immunodeficiency virus.
 2. The method according to claim 1, wherein said primate immunodeficiency virus is a human immunodeficiency virus (HIV) or a simian immunodeficiency virus (SIV).
 3. The method according to claim 2, wherein said HIV is HIV-1 or HIV-2.
 4. The method according to claim 3, wherein said HIV-1 is selected from the group consisting of HIV-1_(IIIB), HIV-1_(UCD1), and HIV-1_(BRU).
 5. The method according to claim 1, wherein said immunogen is a virus infected cell or whole cell-free virus.
 6. The method according to claim 5, wherein said virus is treated in a manner to inactivate or attenuate the virus or said virus is replication-defective.
 7. The method according to claim 6, wherein said virus is inactivated or attenuated by treatment with paraformaldehyde, formalin, phenol, UV light, or elevated temperature.
 8. The method according to claim 1, wherein said immunogen is a polypeptide, or an immunogenic fragment thereof, of said primate immunodeficiency virus.
 9. The method according to claim 8, wherein said polypeptide is encoded by the env, gag, pol, tat, rev, vif, vpr, vpu, or nef gene of said primate immunodeficiency virus.
 10. The method according to claim 8, wherein said polypeptide is an envelope protein selected from the group consisting of gp120 and gp160, or an immunogenic fragment thereof.
 11. The method according to claim 8, wherein said polypeptide is an HIV envelope protein comprising the amino acid sequence shown in SEQ ID NO: 1 or SEQ ID NO: 5, or an immunogenic fragment thereof.
 12. The method according to claim 8, wherein said polypeptide is a p24 protein of HIV, or an immunogenic fragment thereof, or a p27 protein of SIV, or an immunogenic fragment thereof.
 13. The method according to claim 12, wherein said p24 protein is a p24 protein of HIV-1_(UCD1).
 14. The method according to claim 1, wherein said immunogen is a recombinant virus or recombinant expression construct comprising a polynucleotide sequence of a primate immunodeficiency virus.
 15. The method according to claim 14, wherein said polynucleotide sequence is an HIV-1, HIV-2, or SIV sequence.
 16. The method according to claim 14, wherein said polynucleotide sequence comprises one or more env, gag, pol, tat, rev, vif, vpr, vpu, or nef genes, or an immunogenic fragment thereof, of said primate immunodeficiency.
 17. The method according to claim 14, wherein said polynucleotide sequence encodes an HIV gp160, gp120, gp41, p31, p24, p 17, or p7 polypeptide, or an immunogenic fragment thereof.
 18. The method according to claim 1, wherein said method further comprises administering an effective amount of an immunogen derived from a feline immunodeficiency virus (FIV) subsequent to the administration of said immunogen derived from said primate immunodeficiency virus.
 19. The method according to claim 1, wherein said immunogen is provided or administered with a pharmaceutically acceptable carrier or diluent.
 20. The method according to claim 1, wherein said immunogen is provided or administered with one or more adjuvants that increase the immune response of said animal against said immunogen.
 21. The method according to claim 1, wherein said immunogen is administered subcutaneously, intraperitoneally, intramuscularly, orally, or via nasal administration.
 22. The method according to claim 20, wherein said adjuvant is selected from the group consisting of threonyl muramyl dipeptide (MDP), Ribi Adjuvant System including cell wall skeleton (CWS), Freund's complete adjuvant, Freund's incomplete adjuvant, alum, aluminum hydroxide, and saponin.
 23. The method according to claim 1, wherein said immunogen is administered in combination with a cytokine or lymphokine.
 24. The method according to claim 23, wherein said cytokine or lymphokine is a feline cytokine or lymphokine.
 25. The method according to claim 1, wherein said immunogen is administered in combination with interleukin-12, interleukin-15, or interleukin-18.
 26. The method according to claim 1, wherein said immunogen comprises an immunogenic or antigenic peptide of a primate immunodeficiency virus protein.
 27. The method according to claim 1, wherein said immunogen induces the production of T-helper cytokines and cytotoxic T lymphocyte (CTL) cytotoxins.
 28. A method for inhibiting or generating an immune response in a feline animal against FIV, said method comprising administering to said animal an effective amount of an immunogen derived from a primate immunodeficiency virus.
 29. A method for screening for an epitope of a viral protein that is evolutionarily conserved between HIV and FIV, said method comprising: a) isolating of HIV from a long term non-progressor patient infected with said HIV; b) immunizing a feline animal with an immunogen derived from said HIV; c) challenging said feline animal with an infectious FIV; and d) determining whether said feline animal is protected from infection by said FIV, wherein an immunogen that protects said feline animal from infection is indicative of an immunogen that comprises an epitope or epitopes evolutionarily conserved between said HIV and said FIV.
 30. A composition comprising an immunogen derived from a primate immunodeficiency virus and a feline cytokine or lymphokine.
 31. The composition according to claim 30, wherein said feline lymphokine is an interleukin.
 32. The composition according to claim 31, wherein said interleukin is selected from the group consisting of IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-11, IL-12, IL-13, IL-14, IL-15, IL-16, IL-17, IL-18, IL-19, IL-20, IL-21, and IL-22.
 33. The composition according to claim 31, wherein said interleukin is selected from the group consisting of IL-12, IL-15, and IL-18.
 34. The composition according to claim 31, wherein said primate immunodeficiency virus is HIV or FIV.
 35. The composition according to claim 34, wherein said HIV is HIV-1 or HIV-2.
 36. The composition according to claim 35, wherein said HIV-1 virus is selected from the group consisting of HIV-1_(IIIB), HIV-1_(UCD1), and HIV-1_(BRU).
 37. The composition according to claim 31, wherein said immunogen comprises a polynucleotide sequence of an env, pol, gag, tat, rev, vif, vpr, vpu, vpx, or nef gene of HIV.
 38. The composition according to claim 31, wherein said immunogen comprises a gp160, gp120, gp41, p31, p24, p17, or p7 polypeptide, or an immunogenic fragment thereof, of HIV.
 39. The composition according to claim 31, wherein said immunogen is an HIV p24 polypeptide, or an immunogenic fragment thereof, and said interleukin is selected from the group consisting of feline IL-12, IL-15, and IL-18.
 40. A kit comprising in one or more containers: a) an immunogen derived from a primate immunodeficiency virus; and b) a feline cytokine or lymphokine.
 41. The kit according to claim 40, wherein said feline lymphokine is an interleukin.
 42. The kit according to claim 40, wherein said interleukin is selected from the group consisting of IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-11, IL-12, IL-13, IL-14, IL-15, IL-16, IL-17, IL-18, IL-19, IL-20, IL-21, and IL-22.
 43. The kit according to claim 40, wherein said interleukin is selected from the group consisting of IL-12, IL-15, and IL-18.
 44. The kit according to claim 40, wherein said primate immunodeficiency virus is HIV or FIV.
 45. The kit according to claim 44, wherein said HIV is HIV-1 or HIV-2.
 46. The kit according to claim 45, wherein said HIV-1 virus is selected from the group consisting of HIV-1_(IIIB), HIV-1_(UCD1), and HIV-1_(BRU).
 47. The kit according to claim 40, wherein said immunogen comprises a polynucleotide sequence of an env, pol, gag, tat, rev, vif, vpr, vpu, vpx, or nef gene of HIV.
 48. The kit according to claim 40, wherein said immunogen comprises a gp160, gp120, gp41, p31, p24, p17, or p7 polypeptide, or an immunogenic fragment thereof, of HIV.
 49. The kit according to claim 40, wherein said immunogen is an HIV p24 polypeptide, or an immunogenic fragment thereof, and said interleukin is selected from the group consisting of feline IL-12, IL-15, and IL-18.
 50. The method according to claim 28, wherein said immunogen induces the production of T-helper cytokines and cytotoxic T lymphocyte (CTL) cytotoxins.
 51. The method according to claim 28, wherein said immune response is a cellular immune response.
 52. The method according to claim 28, wherein said immune response is a humoral immune response. 